Individual effectiveness in performing physical tasks frequently depends upon an individual's visual skills, such as acuity, contrast sensitivity, and depth perception. For example, skilled crafts such as welding, cabinetmaking, and jewelry-making require accurate perception of objects. Recreational activities such as team and individual sports as well as outdoor recreational pursuits such as mountain climbing and hunting rely on visual performance. For many activities, enhancement of visual skills such as color contrast sensitivity and depth perception is desirable.
Specially adapted optical filters have been suggested that transmit more light at wavelengths overlapping a wavelength range in which a colored object reflects or emits light. See, for example, Moore et al., PCT App. No. PCT/US96/19761. In one example, Moore et al. suggest applying a blue dye to a transparent lens for enhanced viewing of an optic yellow tennis ball. In other examples, so-called “brighteners” are added to improve object visibility. For example, a golf ball cover can include a dye that absorbs radiation at blue or ultraviolet wavelengths in order to produce radiation at longer wavelengths to which the eye is more sensitive, thereby making the golf ball appear whiter.
In many sporting activities, a ball or other object moves rapidly and experiences frequent, rapid accelerations and decelerations. A participant's ability to react to such motion can be limited by the visibility of the ball, and spectator enjoyment is reduced if the spectator is unable to follow the action. While balls and the like have been provided with decorative accents, and are often marked with league and other official insignia, these markings generally do not contribute to visibility.
Superior visibility can be provided by appropriate selection of object colors and color patterns. For example, objects for use in sports, such as soccer balls or other balls, can comprise an exterior having a first exterior region with a spectral reflectance associated with a first color of a pair of enhanced-visibility colors (EVCs) and a second exterior region associated with a second color of the pair. In representative examples, the first color and the second color are substantially complementary and are associated with a luminance contrast of greater than about 50%. In a particular example, the first color is substantially yellow and the second color is substantially blue. In additional examples, the first exterior region and the second exterior region are substantially non-reflective in a spectral window associated with a background. In representative example, the background is grass or blue sky. In additional examples, the first region and the second region are substantially diffusely reflective.
Balls for team or individual sports comprise a cover having a first color region and a second color region configured to be viewable while the ball is in play. Such regions can be configured to, for example, aid in ball location or estimation of ball rotation and/or speed. The first color region and the second color region have spectral reflectances associated with substantially complementary colors. In a representative example, color space locations of the substantially complementary colors are separated by at least 50% of a chromatic blend limit. In additional examples, a chromatic blend line associated with the complementary colors is separated from a central white color space location by less than 25% of the chromatic blend limit. In further examples, color space locations of the substantially complementary colors are separated by at least 75% of a chromatic blend limit. In other examples, a chromatic blend line associated with the complementary colors is separated from a central white color space location by less than 10% of the chromatic blend limit. In additional examples, substantially complementary colors C1 and C2 are associated with respective CIE L-a-b coordinates (C1L, C1a, C1b) and (C2L, C2a, C2b), wherein a color difference CD=√{square root over ((C1a−C2a)2+(C1b−C2b)2)}{square root over ((C1a−C2a)2+(C1b−C2b)2)} is greater than about 50. In further examples, the color difference CD is greater than about 100. In other examples, a total color difference TCD between the first region and the second region is at least about 50 or at least about 100, wherein TCD=√{square root over ((C1a−C2a)2+(C1b−C2b)2+(C1L−C2L)2)}{square root over ((C1a−C2a)2+(C1b−C2b)2+(C1L−C2L)2)}{square root over ((C1a−C2a)2+(C1b−C2b)2+(C1L−C2L)2)}. In additional examples, the substantially complementary colors have a luminance contrast between the first region and the second region of at least 50%.
Methods of selecting colors for a sports item comprise defining a chromatic blend line and selecting a first color location and a second color location on the chromatic blend line, wherein the first color location and the second color location are separated by at least 50% of a chromatic blend limit (CBL). A first color and a second color are selected based on the first color location and the second color location. In a representative example, the chromatic blend line is separated from a central white color space location by less than about 20% of the chromatic blend limit. In additional examples, a color vision deficiency to be accommodated is selected, and the chromatic blend line is selected to be substantially perpendicular to an associated color vision deficiency line of confusion. In further examples, a background spectral window is selected based on an anticipated background for viewing the sports item. A reflectance of at least one of the first color and/or the second color is reduced in at least a portion of the background spectral window. In other examples, the first color and the second color are selected to provide a predetermined luminance contrast.
These and other features are described below with reference to the accompanying drawings.